precision mediump float;

uniform sampler2D u_samplerColor;

varying vec2 v_uv;

void main()
{
	vec4 tex = texture2D(u_samplerColor, v_uv);
	float c = 0.3 * tex.r + 0.59 * tex.g + 0.11 * tex.b;

	gl_FragColor = vec4(c, c, c, 1.0);
}
